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To find the strength of an Alkali

Place 100 grains of the alkali in a tube, and agitate it with about + ounce hot water.

When settled, pour off the clear into a vessel for trial. Repeat this process until nothing soluble remains in the test tube, shown by the last washing not affecting the color of turmeric paper. Care must be taken not to waste the smallest portion of the liquid, as it would render the results inaccurate. deduct 32 from the degrees of Fahrenheit, then multiply the difference by 5, and lastly divide the result by 9.

Thus, 86 degrees Fahrenheit, Deduct 32 Multiplied by 5 Divided by 9)270 Answer. 30 degrees Centigrade. 88. To Reduce degrees of Reaumur to the corresponding degrees of Fahrenheit. Multiply the degrees of Reaumur by 9, divide the result by 4, and then add 32.

Thus, 24° Reaumur.

Multiplied by 9 Divided by 4)216 The he Art of Dyeing. art of fixing coloring matters uniformly and permanently in the fibres of wool, silk, linen, cotton, and other substances. Dyeing is a chemical process, and the mode of its performance depends upon the substance operated on. Thus it is found that the process by which wool is dyed black, would only impart a rusty brown to linen. Wool unites with almost all coloring matters with great facility, silk in the next degree, cotton less easily than silk, and linen with even more difficulty.

Preparatory to the operation of dyeing, each of these substances undergoes a species of preparation to free the fibres from adhering 89. To reduce degrees of Fahrenheit foreign matter, as dirt, grease, &c, which to corresponding degrees of Reaumur. would prevent the absorption of the aqueous Reverse the above process. fluid to be afterwards applied, as well as imapplied, as well as im- 90. To reduce degrees of Reaumur pair the brilliancy of the dye. Wool is cleaned to Centigrade. Add to the degrees of or scoured by means of a weak alkaline lye, Reaumur their one-fourth part. 54 Add 32 - Answer, 86° Fahrenheit.

Thus, 40° Reaumur.

Add one-fourth, 10 Answer 50° Centigrade. - 91. To reduce degrees of Centigrade to Reaumur. Deduct one-fifth part.

Thus, 50° centigrade Deduct one-fifth 10 Answer, 40° Reaumur. 92. Table of corresponding degrees of Fahrenheit, Reaumur and the Centigrade.

Fahrenheit. Reaumur. Centigrade. soap and water, or putrid urine; the latter being very generally used for this purpose.

Silk is cleaned from the natural varnish that covers it, by boiling with white soap and water. Cotton and linen are cleaned with alkaline lyes of more or less density. The substances so prepared are ready to undergo the various operations of dyeing.

Among the various coloring materials employed by dyers, some impart their tints to different substances by simple immersion in their infusions or decoctions, and have hence been called "substantive colors;" but by far the greater number only impart a fugitive dye, unless the fibres of the stuff have been previously filled with some substance which has a strong affinity for the latter on the one hand, and the coloring material on the other.

The substances applied with this intention are called "Mordants," and generally exercise the double property of "fixing" and "striking" the color. Thus, if cotton goods be dyed with a decoction of madder, it will only receive a fugitive and dirty red tinge, but if it be first run through a solution of acetate of alumina, dried at a high temperature, washed, and then run through a madder bath, it will come out a permanent and lively red.

The principal mordants are the acetates of iron and alumina, sulphate of iron, alum, and some other chemical salts. A perfect knowledge of the effect of mordants on different coloring substances is of paramount importance to the dyer. Boiling. 212 80 100 203 76 95 194 72 90 185 68 85 176 64 80 167 60 75 158 56 70 149 52 65 140 48 60 131 44 55 122 40 50 113 36 45 104 32 40 95 28 35 86 24 30 77 20 25 68 16 20 59 12 15 50 8 10 41 4 5 Freezing. 32 0 0 23 - 4 4 - 5 5 14 - 10 5 - 12 -15 - 4 - -20 - 13 All intermediate degrees can be obtained the wood be in the chipped state, it must be 94. Dye Woods, &c. Decoctions of the different woods are prepared for general use in the dye house as they are required. If by the preceding rules. boiled for an hour, in the proportion of 1 pound of wood to 1 gallon of water; a second 48 16 20 - 25 After having received the proper mordants, the goods are dried and rinsed, after which they are passed for a shorter or longer time through an infusion, decoction, or solution of the dyeing materials, which constitute the "dye-bath"; they are again dried and rinsed.

In many cases, the immersion in the dye-bath is repeated, either with the same materials or with others to vary or modify the color.

After the substances have been properly dyed, they are subjected to a thorough rinsing or washing in soft water, until the latter runs off uncolored. boiling is generally given with new wa-dissolve + pound crystallized soda; mix all ter, and the liquor obtained used instead of the solutions together and stir well for some water with more new wood. This second li- time, then allow to stand over night; decant quor is not good for dyeing alone, but when the clear solution which is ready for use. employed instead of water for new wood, 101. To make Caustic Potash. To pound of new wood is sufficient. The second 3 gallons water add 2 pounds either black or liquor may, however, be used as an auxiliary pearl ashes, and boil; when seething add in the dyeing of compound colors, such as newly-slaked lime, until a small quantity browns, drabs and fawns. If the wood be taken out does not effervesce when an acid is ground the same quantity is takennamely, added to it. To test this, take a tumbler half 1 pound for each gallon of the decoction refilled with cold water, put a table-spoonful of quired, and is prepared as follows: -on a the boiling lye into the tumbler, and add a piece of coarse cloth stretched upon a frame, few drops sulphuric acid; if the acid were or laid into a basket, put the ground wood, added to the hot lye, it would spurt up and and place it over a vessel, then pour boiling endanger the operator. When the addition water over the wood until the liquor that runs of acid causes no effervescence, the boiling through is nearly colorless. Barwood and and adding of lime is stopped, and the whole Camwood are always used in the ground allowed to settle; then remove the clear listate, the wood being put into the boiler quid into a vessel having a cover, to prevent along with the goods; no decoctions of these it from taking carbonic acid from the air. woods are made. Decoctions of bark and This serves as a stock for general use. weld are often formed by putting them into a lime sediment remaining may, have some hot The coarse canvas bag, and then suspending it in water added, which will give a strong lye, and boiling water.

The coloring principle of archil is highly soluble in hot water, and is useful in combination with other dyeing materials; but used alone, does not impart a permanent color. may be used for first boils for yarn or heavy cloth.